stringer repair vs replacement

[Billdc]

I have a '92 ski boat that I pulled the deck out of the bow area and bilge that runs from the helm to the transom and did a few core samples of the stringers. 3 of the 4 samples came out nice and clean and dry. The forth, directly under the helm seat, while it felt solid came out dark. The PO replace the floor 2-3 years ago and appears to have sistered a 2x6 PT to the port stringer(which tested well both fore and aft of the motor). I have not removed the deck over this yet so I don't know if the new support runs the entire length or not, I don't believe it does due to what I hope are ribs near the motor mounts. The PO also apears to have thru bolted the new PT lumber to the stringer without ANY sealant, let alone fiberglass. I found this product that appears to halt decay in wood.

http://www.rotdoctor.com/glass/GLrotrepair.html#stringers

Could I remove the sistered PT and fill the holes with this type of product? they also show a nice way to repair a section of rotted stringer with new wood spliced into the gap and glued. Has anybody tried this? I think this would work if there is still half of the depth of the original stringer left to glue to. Much less than half would concern me as to overall strength. If I do have to replace the stringers( I guess if you do one you have to replace both) and want to overbuild them to say 3" thick can I still just use PL and plywood with alternating joints and build up the thickness, say 4 layers of 3/4"?

 

[Woodonglass]

Re: stringer repair vs replacement

I believe, the General Consensus here on the iBoats Forum from Fiberglass Resin Gurus is that the RotDoctor product is nothing more than diluted epoxy resin and is NOT a good option for boat repairs. I don't think you'll find too many of them on here telling you to do it this way. Most of us recommend the conventional, tear out and replace. There's no reason to have a stringer that's 3-4" in width. 3/4 to 1" is usually more than suffiecient due to the fact that it's the fiberglass laminates that provided the strength to the boat not the wood.

 

[GT1000000]

Re: stringer repair vs replacement

+1^^^^

 

[Billdc]

Re: stringer repair vs replacement

Woodonglass, Thanks I was hoping for your input, I've read thru your links and thought that I was going to just replace the entire support system. Someone told me about rotdoctor so I thought I'd ask. I was asking about thicker stringers because the stringers are not very tall, 8 inches max measured on the inboard side at the motor mounts and tapered down fore and aft so I was concerned with holding down a 285HP v8 direct drive. It looks like the originals are 2x's, and I always tend to overbuild at home so I just planned on doubling them up. I think I'm going to wait until fall to start this project so I will start a thread and post pics and ask alot more questions then, but I will be planning thru the summer and wanted to have some idea of what way I'm going. Thanks for the advice.

 

[Woodonglass]

Re: stringer repair vs replacement

Plan on using 3/4" Arauco Plywood, laminated together to give you 1 1/2" thick stringers. Study the drawings in the First link in my signature. It will help you understand how to fabricate and install everything.

 

[Billdc]

Re: stringer repair vs replacement

Is Arauco the same as marine plywood? I have a local supplier for marine and a quick search at lowes did not turn up arauco plywood.

 

[Woodonglass]

Re: stringer repair vs replacement

No, It's exterior Grade. Marine Grade is expensive but very good to use if you want to pay the price.

 

[Scott Danforth]

Re: stringer repair vs replacement

Arauco is one of the manufacturers of exterior grade ACX. it can be found at Lowes, Menards, and many other home improvement companies.